Cooling systems in aircraft are used primarily for air conditioning purposes in a passenger cabin and for refrigerating purposes in an aircraft galley. Such cooling systems include a substantial number of pipes that cannot be conveniently installed in their full length in the system. Therefore, it is necessary to divide the pipes into pipe sections which must be interconnected by pressure- and fluid-tight pipe junctions. These pipes transport either air or a coolant. The pipe ends of individual pipe sections are interconnected either by metal or rubber-type pipe junction elements. Metal junction elements are usually formed as hard or stiff sleeves while rubber or elastomeric type junctions are frequently formed as flexible soft bellows. Both types of junction elements are secured to the respective pipe ends that face each other by overlapping the pipe ends and by so-called hose clamps constructed as single or double shell clamps. Two such clamps are required for each junction for tying each end of the junction element to a respective pipe end.
These hose clamps are conventionally made of stainless steel and are used by most aircraft manufacturers such as Airbus, Boeing, McDonnell Douglas, Tupolev and so forth. One drawback of so-called junctions with hose clamps is seen in that the required fluid and pressure tightness for positive and negative pressures is not always achieved with the desired certainty or cannot be maintained for a desirable useful life of such pipe junctions. This problem requires, where it exists, substantial additional work by individually retightening the hose clamps, for example prior to delivery of an aircraft to a customer or during repair and maintenance operations. This problem is even aggravated where individual customers have special air conditioning and/or cooling requirements. Another drawback is seen in the fact that keeping substantial numbers of hose clamps of different sizes in stock is not very efficient. Moreover, conventional pipe junctions with hose clamps in an aircraft have a cumulative weight adding effect since all hose clamps together can have a substantial weight.
German Patent Publication DE-OS 25 27 838 (Lesk) relates to pipe junctions particularly for air pressure and suction pipes in which the junctions are formed between pipe ends facing each other by a shrink hose section. Lesk discloses various types of pipe ends that face each other and are joined to each other by a shrunk hose section of shrinkable material. Flanged pipe ends and pipe ends inserted one into the other are bridged and interconnected a shrunk hose section. No suggestions are made that such pipe junctions are suitable for use under the rigorous operating conditions in aircraft cooling systems which must also satisfy stringent government regulations applicable to aircraft cooling systems.